Fluid operated switch



y 1941. J. c D. JENSEN 2,249,208

FLUID! OPERATED SWITCH Filed Dec. 1, 1957' 2 Sheets-Sheet l Jo/m 6. [Z Jensen July 15, 1941. I J. c. D. JENSEN 2,249,208

FLUID'OEVERATED SWITCH Filed Dec. 1, 193'? 2 Sheets-Sheet 2 13 asl 10 46 15 44 I I1 1 -z51z I INVEN'I'OR JO/i/I 6. 0 Jensen Patented July 15, 1941 2,249,208 FLUID OPERATED swrron John C. D. Jensen, Rochester, N. Y., assignor, by mesne assignments, to Bendix Aviation Corporation, South Bend, 1nd,, a corporation of Delaware Application December 1, 1937, Serial No. 177,576

19 Claims.

The present invention relates to'a fluid operated switch and more particular y to a hydraulic switch which is responsive to uid pressure in a hydraulic braking system of an automobile and for controlling the-lighting of a stoplight signal thereon when said braking system is operated.

Since such a switch may be connected into the hydraulic brake system of an automobile, it is vitally important that the switch be absolutely fluid tight. It is also essential that said switch shall not develop leaks under the severest conditions and/or shall not be subject to I rupture or short circuiting even after thousands of actu-ations of the switch.

The primary object of the present invention is the provision in a fluid operated switch of a dielectric member which improves the fluid sealing and/or the insulation between the internal switch elements and the metallic casing therefor.

Another object is the provision in a fluid operated switch of. an anti-friction intermediate silver, which is not corroded by the vapors from the hydraulic fluid and/or providing recesses around the contacts for receiving any products of corrosion and preventing other parts of the switch from being rendered inoperative.

Other and further objects of the invention and the manner of their attainment will be apparent to those skilled in the art by the description that follows.

Reference is hereby made to the accompanying drawings, wherein similar reference characters designate similar elements and wherein:

Fig. l is a longitudinal cross-section of the preferred form of my fluid operated switch; Fig. 2 is a transverse cross-section of said preferred fluid operated switch and is taken on the line 22 of Fig.1; Fig. 3 is a longitudinal cross-section of a fluid operated switch including contacts composed of a noble metal; Fig 3a is a perspective View of a bi-metallic cap member; Fig. 4 is a transverse cross-section taken on the section of a fluid operated switch provided with recesses around the contacts; Fig. 6 is a transverse cross-section taken on the line 6-6 of Fig. 5; and Fig. 7 is a longitudinal cross-section of a fluid operated switch including a dielectric member according to the invention but without a compressible or rubber diaphragm.

In all of the aforementioned drawings the fluid operated switches and parts thereof are drawn to an enlarged scale for better illustration of the various features.

All forms of the fluid operated switches disclosed herein have many structural features in common which will first .be described. The switch assemblies are housed within a hollow metallic casing l0 which is preferably of hexagonal formation, which has an internal annular seat II, and which includes at one end thereof a threaded nipple l2 adapted in a known manner for connection to a hydraulic braking system. An insulating insert or member l3 encloses the other end of casing l0 and is provided with an annular shoulder H for co-operation with an overhanging flange l5 of easing I 0 and which flange I5 is peened over in a well understood manner during the assembly of the switch to secure all of its parts in fluid tight relationship.

"A pair of terminal posts I6 and I1 are each provided at one end with threaded holes l8 to facilitate the connection of electrical conductors, and each have at the other end a restricted portion IS with a knurled section 20 embeddedin the insulating member l3. Said insulating member I3 is molded of any suitable plastic material,

such as a phenol condensation product.

The interior of metallic casing I0 is in all forms of the fluid operated switch divided into a fluid chamber 9 and a switch chamber 1 by a flexible metallic cap 2| concave toward said switch chamber and having an annularrim 22, and by a dielectric member or. cap 23 which covers said metallic cap 2| and which also has an annular rim 24 for insulating the metallic cap 2| from the metallic casing I0. Said dielectric member 23 may be composed from any suit able insulating sheet material and vulcanized fiber has been found to be very satisfactory. A compressible member or rubber diaphragm 25 is preferably interposed between said dielectric cap 23 and said annular seat II to insure a fluid tight seal therebetween although it is to be I invention and Figs. 1 and 2, the insulating member i3 is provided with a circular recess 26 in which the switch contact members are located. One such switch contact member comprises a contact 21 driven into the end of terminal post It while the other switch contact member comprises a switch arm 2| secured by a rivet 29 to the end of terminal post l1 and carrying a contact 30. A coil spring 3| is positioned within a hole 32 in insulating'member I2 and bears on switch arm 28 normally to hold contact spaced from contact 21.

An intermediate member is interposed between the metal cap 2| and switch arm 2! and is supported by a mounting means for free rolling movement upon flexing of said metal cap 2|. Such an intermediate member is very advantageously provided as a steel ball 23 which can be inexpensively manufactured tovery accurate dimensions and with extreme hardness for maximum wearing quality. Said mounting means may comprise a partition or circular disc 3 which is provided with a central opening 35 within which ball bearing 23 moves primarily with rolling friction. The elements |3, |6, H, 28 and 3| comprise the switch assembly I.

This preferred form of fluid operated switch is readily and accurately assembled by inserting into the hollow casing HI, in the order named, the rubber diaphragm 25, the dielectric cap 23, the metallic cap 2|, the circular disc 34, the steel ball 23, and the insulating member I! carrying the switch arm 28. The flange I! of casing i0 is then peened over against shoulder ll of insulating member l2, and the rubber diaphragm 25 and dielectric cap 22 tightly seal the switch chamber to prevent entry of the hydraulic fluid or fluid vapors thereinto.

When the pressure is increased in the hydraulic braking system, the rubber diaphragm 25, dielectric cap 23, and metallic cap 2| are all flexed until said metallic cap 2i is flattened against circular disc 34. At the same time, steel ball 33 is rolled within central opening 35 to move switch arm 28 and close contacts 21 and 30 against the action of coil spring 3| Such construction for a fluid operated switch is particularly advantageous because the switches can be rapidly and accurately assembled with a minimum of rejected switches which rejects represent a total loss since said rejects can not be re-opened for re-assembly without considerable difliculty and the destruction of the casing I 0.

The hydraulic fluids commonly employed in hydraulic braking systems, such as a mixture of diacetone and castor oil, emit vapors which are extremely corrosive and which in time may,

in spite of the tight seal provided by rubber diaphragm 25 and dielectric member 23, penetrate or be diffused into the switch chamber to cause corrosion of the contacts 21 and 30. Consequently, said contacts 21 and 3. are composed of a metal or alloy which will not only resist such corrosion but which metal or alloy forms a product of corrosion which is a comparatively good conductor of electricity. Such noble metals may be silver, platinum, gold, iridium, etc., and their alloys, but contacts essentially consisting of silver are preferred.

Another manner of providing contact members composed of a noble metal or alloy thereof is illustrated in Figs. 3 and 4. As before the fluid operated switch comprises a hollow metallic casing in and an insulating member |3 in which terminal posts I! and I! are embedded. Said insulating member I! is provided with an annular recess 38 and has an internal surface 31 which is provided with a central recess 3|. Standard round headed contacts 39 and 4. are mounted within said central recess 38 and each includes, respectively, stems II and 42 which are driven into respective terminal posts I and I1, eccentrically thereof. The eccentricities of said stems 4| and 42 with respect to the corresponding terminal posts I6 and I1, extend towardeach other and are such that the adjacent edges of contacts 29 and III are close together.

The metallic cap 2| is normally concave toward contacts 39 and 40 and has an annular rim 22 fitting into the annular recess 36 of insulating member l3. Said metallic cap 2| is preferably composed of bi-metallic material including a sheet of a rugged, resilient foundation metal, such as phosphor bronze, and an extremely thin strip 41 of a noble metal, such as silver or silver alloy, which is embedded as by hot rolling into the foundation metal of said cap 2|. Such bimetallic material is peculiarly suited for fluid operated switches, since a highly conductive and corrosion resistant contact bridge for the noble metal contacts 39 and 4. is obtained without sacriflce in strength or resiliency of the cap proper and can be fabricated at only a fraction of the cost of other types of eifective contact bridges. I

In view of the'p'roximity of the adjacent edges of contacts 2! and 40 with respect'to each other by reason of the previously explained eccentric mounting thereof in terminal posts It and H, the strip 42 of noble metal :may be of sufllcient width to bridge contacts 29 and ll irrespective of the relative diametral position of strip 43. Nevertheless, it is preferred to locate bi-metal cap 2| so that the strip 42 extends longitudinally across contacts II and 4., as indicated by the dot dash lines in Fig. 4, and a locating connection may be provided to insure such relative positioning of cap member 2| and insulating member l8. Such locating connection may comprise a lug 22 projecting from the annular rim 22 of bi-metal cap 2| or a pair of lugs 22' each adjacent respective ends of the silver strip 43. One or more notches 36 are provided in insulating member I3 adjacent the annular. recess 26 therein, see Fig. 3, and are, of course, preferably located in line with the contacts 39 and ll so that the strip 43 extends longitudinally of said contacts 39 and II when the lugs 22 are engaged in the notches 36'.

On the other hand, the use of noble metal contacts may not be expedient and the corrosion of the contacts by the vapors from the hydraulic fluid must be accepted. However, if the corroding contacts are flush with the surface of the insulating member I3, the products of corrosion build up and soon deform the metal cap 2| to cause rupture of the same or to create a high contact resistance, or both. In any event the fluid operated switch may soon become inoperative.

In order to overcome these difllculties caused by products of corrosion, the form of fluid operated switch illustrated in Figs. 5 and 6 has been devised. Such a switch comprises a hollow casing l0, annular seat I therein, and a threaded nipple |2. The insulating member I! has a shoulder ll engaged by the overhangi g flange I! of casing l0 and has terminal posts I and I1 embedded in the molded insulating member H. The inner ends of terminal posts IS and H are available throughthe internal surface I! of in- I sulating member It to constitute contacts 44 and 45. The annular rim 22 of metallic cap 2| flts into the annular recess 36 provided in insulating member i3. The dielectric cap 23 covers metallic cap 2! and the annular dielectric rim 24 insulates the'annular rim 22 of metallic cap 2| from the metallic casing ll. A rubber diaphragm 25 is also preferably interposed between dielectric member 23 and annular seat H.

This form of fluid operated switch is also assembled with the outer margins of metallic cap 2i, dielectric member 23 and rubber diaphragm 25 held by overhanging flange-i in fluid tight relationship between insulating member 13 and annular seat ll of casing 10. However, when contacts 44 and 45 are made of corrodible metal,

such as brass, the vapors from the hydraulic fluid cause considerable corrosion and receptacles for the products of corrosion are provided in the internal surface 31 of insulating member 13. Such receptacles may be in the form of circular recesses 46 and 41, respectively encircling contacts 44 and 45. As a result, actuation of the metallic cap 2| by the creation of pressure in the hydraulic braking system will wipe the products of corrosion into said recesses 46 and "so that deposits of non-conducting oxidesdo not build up on the ends of contacts 44 and 45 to deform and ultimately rupture cap 2l"or to increase the contact resistance to said cap 2|.

' The outstanding feature of my invention is the provision of the dielectric cap member 23 to act both as an insulating and as a sealing member.

- the appended claims contemplates the dielectric cap member 23 alone or in conjunction with the rubber diaphragm 25. C

The cap member 2| may be composed of any suitable. flexible, strong and. high conductance material but preferably is made of phosphor bronze or a bi-metal of phosphor bronze foundation with a silver strip on the inner concave face thereof. Said cap member 2i may also be conical, spherical or have any other formation that normally spaces the same from the contacts and which under the fluid pressure of the switch engages the contacts. Other suitable materials than those disclosed herein may be used without departing from the-scope olmy invention except as specified in the following claims.

Having now particularly described my invention what I desire to secure by Letters Patent of the'United States and what I claim is:

1. In a fluid operated switch, the combination with a hollow metallic casing having one end adapted for connection to a hydraulic braking system, an insulating member inserted in and closing the other end of said casing and including a pair of contact members, a circular metallic cap normally concave toward said contact members and formed with a cylindrical flange at its outer edge, a dielectric circular cap member also formed with a cylindrical flange at its outer edge and covering said cap and having its flange between said metallic cap and said casing, and means for maintaining said insulating member, metallic cap and dielectric member in fluid tight relationship within said casing.

2. In a fluid operated switch, the combination with a hollow metallic casing having one end adapted for connection to a hydraulic braking tween said casing and the cylindrical flange of the metallic cap and overlapping the latter, and means for pressing said insulating member, said metallic cap and said dielectric cap into fluid tight relationship, 3. In a fluid operated switch, the combination.

with a hollow metallic casing having one end adapted for connection to a hydraulic braking system, an insulating member inserted in and closing the other end of said casing and including a pair of contact members, a circular metallic cap normally concave toward said contact members and formed with a cylindrical flange at its outer edge comprising an annular rim extending toward said contact members, a dielectric circular cap member also formed with a cylind'rical flange at its outer edge and covering said metallic cap and having its flange formed as an annular rim between said casing and said annular rim-of the metallic cap, a compressible member between said dielectric cap and said casing, and means for pressing said insulating member, said metallic cap, said dielectric cap and said compressible member into fluid tight relationship. v

4. In a fluid operated switch, the combination with a hollow metallic casing having one end adapted for connection to a hydraulic braking system, an insulating member inserted in and closing the other end of said casing and including a pair of contact members, a circular metallic cap normally concave toward said contact members and formed with a cylindrical flange at its outer edge, a dielectric circular cap member also formed with a cylindrical flange at its outer edge, composed of vulcanized flber and covering said cap and having its flange between the flange of said metallic cap and said casing, and means formaintaining said insulating member, metallic cap and dielectric member in fluid tight relationship within said casing.

5. In a fluid operated switch, the combination with a hollow casing having one end adapted for connection-to a hydraulic braking system which contains a fluid emitting penetrating and cor- I rosive vapor, an insulating member enclosing the flexing thereof by the fluid pressure in said braking system, said internal surface of the insulating member being provided with a pair of recesses,each of which is adjacent to a contact and for receiving the product of corrosion between said contact and the corrosive vapor which may penetrate into said switch chamber.

6. In a fluid operated switch, the combination witha hollow casing having one end adapted for system, an insulating member inserted in and connection to a hydraulic braking system which contains a fluid emitting penetrating and corrosive vapors, an insulating member enclosing the other end of said casing and having an internal surface, a metallic cap normally concave toward said surface of said insulating member and dividing the interior of said casing into afluid chamber and into a switch chamber, and fluid sealing means between said cap and said casing, of a means for clamping said metallic cap and said sealing means between said insulating member and said casing, and a pair of contacts extending through said insulating member and located to be engaged by said metallic cap upon flexing thereof by the fluid pressure in said braking system, said internal surface of the insulating member being provided with a pair of circular recesses each of which encircles one of said contacts.

'7. In a fluid operated switch, the combination with a casing having one end adapted for connection to a hydraulic braking system, and an insulating member enclosing the other end of said casing, including a pair of contacts, and provided with an annular recess and a notch, of a cap member including an annular rim and a lug, and composed of a bi-metallic material including a thin strip of high conductance metal on the surface thereof adjacent said contacts, said lug fitting into said notch to position said bi-metallic cap with its thin strip extending longitudinally across said contacts.

8. A fluid operated switch comprising a hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a dielectric disk inserted in the open end of said casing so as to separate said open end from said outlet, a guide disk inserted in the open end of said casing and lying between said dielectric disk and said open end, an intermediate member associated with and guided by said guide disk, a switch member contacted by said intermediate memberand arranged to be operated thereby, contact members arranged to be connected by said switch member when it is operated by said intermediate member, and an insulating member carrying said contact members and inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

9. A fluid operated switch comprising a hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a dielectric disk inserted in the open end of said casing so as to separate said open end from said outlet, a guide disk inserted in the open-end of said casing and lying between said dielectric disk and said open end, a ball member associated with and guided by said guide disk contacting said dielectric member on one side, a switch member contacted by said ball member and arranged to be operated thereby, contactmembers arranged to be connected by said switch member when it is operated by said ball, and an insulating member carrying said contact members and inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

10. A fluid operated switch comprising a hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a sealing disk inserted in the open end of said casing so as to separate said open end from said outlet, a dielectric disk inserted in the open end of said casing and lying between said sealing disk and said open end, a guide disk inserted in the open end of said casing and lying between said dielectric disk and said open end, an intermediate member associated with and guided by said guide disk, a switch member contacted by said intermediate member and arranged to be operated thereby, contact members arranged to be connected by said switch member when it is operated by said intermediate member, and an insulating member carrying said contact members and inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

11. A fluid operated switch comprising a. hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a sealing disk inserted in the open end of said casing so as to separate said open end from said outlet, a dielectric disk inserted in the open end of said casing and lying between said sealing disk and said open end, a switch member arranged to be operated by said dielectric disk, contact members arranged to be connected by said switch member when it is operated by said dielectric disk, and 'an insulating member carrying said contact members and inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

12. A fluid operated switch comprising a hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a rubber disk inserted in the open'end of said casing so as to separate said open end from said outlet and formed with a cylindrical flange, a dielectric disk inserted in the open end of said casing, lying between said rubber disk and said open end and formed with a cylindrical flange which is'separated from the casing by the flange of the rubber disk, a guide disk inserted in the open end of said casing lying between said dielectric disk and said open end, an intermediate member associated with and guided by said guide disk, a switch member contacted by said intermediate member and arranged to be operated thereby, contact members arranged to be connected by said switch member when it is operated by said intermediate, member, and an insulating member carrying said contact membersand inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

13. A fluid operated switch comprising a hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a. dielectric disk inserted in the open end of said casing so as to separate said open end from said outlet and formed with a cylindrical flange, a switch member arranged to be operated by said dielectric disk, contact members arranged to be connected by said switch member when it is operated by said dielectric disk, and an insulating member carrying said contact members and inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

14. A fluid operated switch comprising a hollow casing formed with one open end and with a fluid outlet adjacent the opposite end, a dielectric disk inserted in the open end of said casing so as to separate said open end from said outlet, a guide disk inserted in the open end of said casing and lying between said dielectric disk and said open end, an intermediate member associated with and guided by said guide disk, a switch member comprising a switch arm conmoved to operated position'by said intermediate member, and an insulating member carrying said a contact members and inserted in the open end of said casing and positioned toward said open end from the switch member and closing said open end.

15. In a fluid operated switch, the combination with a hollow casing having one end adapted for connection to a hydraulic braking system which contains a fluid emitting penetrating and corrosive vapors, an insulating member inserted in and closing the other end of said casing and having an internal surface normally concave toward said other end of the casing, a fluid sealing means dividing the interior of said casing into a fluid chamber and into a switch chamher, a means for clamping said sealing means between said insulating member and said casing, a switch member between said sealing member and said insulating member, and a pair of contacts extending through said insulating member and located to be engaged by said switch member upon flexing of said sealing member by the fluid pressure in said braking system, said internal surface of the insulating member being provided with a pair of circular recesses, each of which encircles one of said contacts.

16. In a fluid operated switch, the combination with a hollow casing having one end adapted for connection to a hydraulic braking system which contains a fluid emitting penetrating and corrosive vapors, an insulating member inserted in and closing the other end of said casing and having an internal surface, a fluid sealing means dividing the interior of said easing into a fluid chamber and into a switch chamber, a means for clamping said sealing means between said insulating member and said casing, a switch member between said sealing member and said insulating member, and a pair of contacts extending through said insulating member and located to be engaged by said switch member upon flexing of said sealing member by the fluid pressure in said braking system, said internal surface of the insulating member being provided with a pair of circular recesses, each of which encircles one of said contacts.

17. In a device of the class described a cupshaped container, a diaphragm in the container, a pressure chamber formed between the container and the diaphragm having an inlet for communication with a source of pressure, a supporting plate adjacent the diaphragm to bear the stresses during periods of high pressure resulting in maximum flexure of the diaphragm, a unitary switch assembly having within itself means for making and breaking a circuit and positioned in the container, an inturned flange on the cup-shaped container cooperating with the switch assembly whereby the supporting plate transmits stresses to the container, and an actuating means cooperating with the diaphragm to actuate the switch to control an electric circuit.

18. In a device of the class described a cupshaped container; a diaphragm in the container; a pressure chamber formed between the contalner and the diaphragm having an inlet for communication with a source of pressure; a supporting plate adjacent the diaphragm having an opening and arranged to bear the stresses during the periods of high pressure resulting in maximum flexure of the diaphragm; a unitary switch assembly having within itself means for making and breaking a circuit and positioned in the 3ontainer; an inturned flange on the cup-shaped container cooperating with the switch assembly whereby the supporting plate transmits stresses to the container; and an actuating means cooperating with the diaphragm and extending through the opening in the supporting plate to actuate the switch to control an electric circuit.

19. In a device of the class described a cupshaped container; a diaphragm in the container; a pressure chamber formed between the container and the diaphragm having an inlet for communication with a source of pressure; a supporting plate adjacent the diaphragm having an opening and arranged to hear the stresses during periods of high pressure resulting in maximum flexure of the diaphragm; a unitary switch assembly positioned'in the container, said assem bly including an insulating member, a pair of electrical conducting members extending through said insulating member, a flexible member secured at one end to one of said conducting members and arranged to be moved into contact with said other conducting member; an inturned flange on the cup=shaped container cooperating with the switch assembly whereby the supporting plate transmits stresses to the container: and an actuating means cooperating with the diaphragm and extending through the opening in the supporting plate to actuate the switch to control said flexible member to move it into and out of contact as aforesaid to make and break an electric circuit.

JOHN C. D. JENSEN. 

